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<ol class="chapter"><li class="chapter-item expanded "><a href="../intro.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../translations.html"><strong aria-hidden="true">1.1.</strong> Translations</a></li></ol></li><li class="chapter-item expanded "><a href="../idioms/index.html"><strong aria-hidden="true">2.</strong> Idioms</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../idioms/coercion-arguments.html"><strong aria-hidden="true">2.1.</strong> Use borrowed types for arguments</a></li><li class="chapter-item expanded "><a href="../idioms/concat-format.html"><strong aria-hidden="true">2.2.</strong> Concatenating Strings with format!</a></li><li class="chapter-item expanded "><a href="../idioms/ctor.html"><strong aria-hidden="true">2.3.</strong> Constructor</a></li><li class="chapter-item expanded "><a href="../idioms/default.html"><strong aria-hidden="true">2.4.</strong> The Default Trait</a></li><li class="chapter-item expanded "><a href="../idioms/deref.html"><strong aria-hidden="true">2.5.</strong> Collections Are Smart Pointers</a></li><li class="chapter-item expanded "><a href="../idioms/dtor-finally.html"><strong aria-hidden="true">2.6.</strong> Finalisation in Destructors</a></li><li class="chapter-item expanded "><a href="../idioms/mem-replace.html"><strong aria-hidden="true">2.7.</strong> mem::{take(_), replace(_)}</a></li><li class="chapter-item expanded "><a href="../idioms/on-stack-dyn-dispatch.html"><strong aria-hidden="true">2.8.</strong> On-Stack Dynamic Dispatch</a></li><li class="chapter-item expanded "><a href="../idioms/ffi/intro.html"><strong aria-hidden="true">2.9.</strong> Foreign function interface (FFI)</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../idioms/ffi/errors.html"><strong aria-hidden="true">2.9.1.</strong> Idiomatic Errors</a></li><li class="chapter-item expanded "><a href="../idioms/ffi/accepting-strings.html"><strong aria-hidden="true">2.9.2.</strong> Accepting Strings</a></li><li class="chapter-item expanded "><a href="../idioms/ffi/passing-strings.html"><strong aria-hidden="true">2.9.3.</strong> Passing Strings</a></li></ol></li><li class="chapter-item expanded "><a href="../idioms/option-iter.html"><strong aria-hidden="true">2.10.</strong> Iterating over an Option</a></li><li class="chapter-item expanded "><a href="../idioms/pass-var-to-closure.html"><strong aria-hidden="true">2.11.</strong> Pass Variables to Closure</a></li><li class="chapter-item expanded "><a href="../idioms/priv-extend.html"><strong aria-hidden="true">2.12.</strong> Privacy For Extensibility</a></li><li class="chapter-item expanded "><a href="../idioms/rustdoc-init.html" class="active"><strong aria-hidden="true">2.13.</strong> Easy doc initialization</a></li><li class="chapter-item expanded "><a href="../idioms/temporary-mutability.html"><strong aria-hidden="true">2.14.</strong> Temporary mutability</a></li><li class="chapter-item expanded "><a href="../idioms/return-consumed-arg-on-error.html"><strong aria-hidden="true">2.15.</strong> Return consumed arg on error</a></li></ol></li><li class="chapter-item expanded "><a href="../patterns/index.html"><strong aria-hidden="true">3.</strong> Design Patterns</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../patterns/behavioural/intro.html"><strong aria-hidden="true">3.1.</strong> Behavioural</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../patterns/behavioural/command.html"><strong aria-hidden="true">3.1.1.</strong> Command</a></li><li class="chapter-item expanded "><a href="../patterns/behavioural/interpreter.html"><strong aria-hidden="true">3.1.2.</strong> Interpreter</a></li><li class="chapter-item expanded "><a href="../patterns/behavioural/newtype.html"><strong aria-hidden="true">3.1.3.</strong> Newtype</a></li><li class="chapter-item expanded "><a href="../patterns/behavioural/RAII.html"><strong aria-hidden="true">3.1.4.</strong> RAII Guards</a></li><li class="chapter-item expanded "><a href="../patterns/behavioural/strategy.html"><strong aria-hidden="true">3.1.5.</strong> Strategy</a></li><li class="chapter-item expanded "><a href="../patterns/behavioural/visitor.html"><strong aria-hidden="true">3.1.6.</strong> Visitor</a></li></ol></li><li class="chapter-item expanded "><a href="../patterns/creational/intro.html"><strong aria-hidden="true">3.2.</strong> Creational</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../patterns/creational/builder.html"><strong aria-hidden="true">3.2.1.</strong> Builder</a></li><li class="chapter-item expanded "><a href="../patterns/creational/fold.html"><strong aria-hidden="true">3.2.2.</strong> Fold</a></li></ol></li><li class="chapter-item expanded "><a href="../patterns/structural/intro.html"><strong aria-hidden="true">3.3.</strong> Structural</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../patterns/structural/compose-structs.html"><strong aria-hidden="true">3.3.1.</strong> Compose Structs</a></li><li class="chapter-item expanded "><a href="../patterns/structural/small-crates.html"><strong aria-hidden="true">3.3.2.</strong> Prefer Small Crates</a></li><li class="chapter-item expanded "><a href="../patterns/structural/unsafe-mods.html"><strong aria-hidden="true">3.3.3.</strong> Contain unsafety in small modules</a></li></ol></li><li class="chapter-item expanded "><a href="../patterns/ffi/intro.html"><strong aria-hidden="true">3.4.</strong> Foreign function interface (FFI)</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../patterns/ffi/export.html"><strong aria-hidden="true">3.4.1.</strong> Object-Based APIs</a></li><li class="chapter-item expanded "><a href="../patterns/ffi/wrappers.html"><strong aria-hidden="true">3.4.2.</strong> Type Consolidation into Wrappers</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../anti_patterns/index.html"><strong aria-hidden="true">4.</strong> Anti-patterns</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../anti_patterns/borrow_clone.html"><strong aria-hidden="true">4.1.</strong> Clone to satisfy the borrow checker</a></li><li class="chapter-item expanded "><a href="../anti_patterns/deny-warnings.html"><strong aria-hidden="true">4.2.</strong> #[deny(warnings)]</a></li><li class="chapter-item expanded "><a href="../anti_patterns/deref.html"><strong aria-hidden="true">4.3.</strong> Deref Polymorphism</a></li></ol></li><li class="chapter-item expanded "><a href="../functional/index.html"><strong aria-hidden="true">5.</strong> Functional Programming</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../functional/paradigms.html"><strong aria-hidden="true">5.1.</strong> Programming paradigms</a></li><li class="chapter-item expanded "><a href="../functional/generics-type-classes.html"><strong aria-hidden="true">5.2.</strong> Generics as Type Classes</a></li><li class="chapter-item expanded "><a href="../functional/lenses.html"><strong aria-hidden="true">5.3.</strong> Lenses and Prisms</a></li></ol></li><li class="chapter-item expanded "><a href="../additional_resources/index.html"><strong aria-hidden="true">6.</strong> Additional Resources</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../additional_resources/design-principles.html"><strong aria-hidden="true">6.1.</strong> Design principles</a></li></ol></li></ol>
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<h1 id="easy-doc-initialization"><a class="header" href="#easy-doc-initialization">Easy doc initialization</a></h1>
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<h2 id="description"><a class="header" href="#description">Description</a></h2>
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<p>If a struct takes significant effort to initialize when writing docs, it can be
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quicker to wrap your example with a helper function which takes the struct as an
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argument.</p>
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<h2 id="motivation"><a class="header" href="#motivation">Motivation</a></h2>
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<p>Sometimes there is a struct with multiple or complicated parameters and several
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methods. Each of these methods should have examples.</p>
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<p>For example:</p>
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<pre><code class="language-rust ignore">struct Connection {
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name: String,
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stream: TcpStream,
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}
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impl Connection {
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/// Sends a request over the connection.
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///
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/// # Example
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/// ```no_run
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/// # // Boilerplate are required to get an example working.
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/// # let stream = TcpStream::connect("127.0.0.1:34254");
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/// # let connection = Connection { name: "foo".to_owned(), stream };
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/// # let request = Request::new("RequestId", RequestType::Get, "payload");
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/// let response = connection.send_request(request);
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/// assert!(response.is_ok());
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/// ```
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fn send_request(&self, request: Request) -> Result<Status, SendErr> {
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// ...
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}
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/// Oh no, all that boilerplate needs to be repeated here!
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fn check_status(&self) -> Status {
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// ...
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}
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}</code></pre>
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<h2 id="example"><a class="header" href="#example">Example</a></h2>
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<p>Instead of typing all of this boilerplate to create a <code>Connection</code> and
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<code>Request</code>, it is easier to just create a wrapping helper function which takes
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them as arguments:</p>
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<pre><code class="language-rust ignore">struct Connection {
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name: String,
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stream: TcpStream,
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}
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impl Connection {
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/// Sends a request over the connection.
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///
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/// # Example
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/// ```
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/// # fn call_send(connection: Connection, request: Request) {
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/// let response = connection.send_request(request);
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/// assert!(response.is_ok());
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/// # }
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/// ```
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fn send_request(&self, request: Request) {
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// ...
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}
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}</code></pre>
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<p><strong>Note</strong> in the above example the line <code>assert!(response.is_ok());</code> will not
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actually run while testing because it is inside a function which is never
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invoked.</p>
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<h2 id="advantages"><a class="header" href="#advantages">Advantages</a></h2>
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<p>This is much more concise and avoids repetitive code in examples.</p>
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<h2 id="disadvantages"><a class="header" href="#disadvantages">Disadvantages</a></h2>
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<p>As example is in a function, the code will not be tested. Though it will still be
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checked to make sure it compiles when running a <code>cargo test</code>. So this pattern is
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most useful when you need <code>no_run</code>. With this, you do not need to add <code>no_run</code>.</p>
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<h2 id="discussion"><a class="header" href="#discussion">Discussion</a></h2>
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<p>If assertions are not required this pattern works well.</p>
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<p>If they are, an alternative can be to create a public method to create a helper
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instance which is annotated with <code>#[doc(hidden)]</code> (so that users won't see it).
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Then this method can be called inside of rustdoc because it is part of the
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crate's public API.</p>
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